Rescuers using cranes and heavy machinery have been searching the wreckage of trains involved in a deadly collision that sent Greece into national mourning and prompted strikes and protests over rail safety.

The death toll from the head-on crash involving a passenger and freight train remained at 43 as crews check the burned out and twisted carriages for more bodies.

More than 50 people remain in hospital, mostly in the central Greek city of Larissa, with some in a serious condition.

Railway workers’ associations called strikes, halting national services and the subway in Athens, to protest against working conditions and what they described as a lack of modernisation of the Greek rail system.

Wednesday’s collision occurred near the small town of Tempe in northern Greece, when a freight train loaded with heavy construction equipment smashed into a passenger service on Greece’s busiest line between Athens and the country’s second largest city, Thessaloniki.

More than 300 people were on the train, many of them students returning from a holiday weekend and annual Carnival celebrations.

As Greece reeled from its deadliest ever train disaster, Pope Francis and European leaders sent messages of sympathy.

Among them were the Turkish foreign minister Mevlut Cavusoglu, whose country is recovering from devastating earthquakes last month.

Ukrainian president Volodymyr Zelensky sent a message in Greek, writing: “The people of Ukraine share the pain of the families of the victims. We wish a speedy recovery to all the injured.”

A stationmaster arrested following the rail disaster is due to appear in court on Thursday as a judicial inquiry tries to establish why the two trains traveling in opposite directions were on the same track.

Transport Minister Kostas Karamanlis resigned following the crash, with his replacement tasked with setting up an independent inquiry to look into the causes of the accident.

“Responsibility will be assigned,” Prime Minister Kyriakos Mitsotakis said in a televised address late on Wednesday after visiting the scene of the collision. “We will work so that the words ‘never again’… will not remain an empty pledge. That I promise you.”